The field of the present invention is tensioned screens having utility for vibratory separation.
Vibratory separators have long been used for separation of materials, both wet and dry. Such separators have been classically divided into rectangular screen separators and circular screen separators. An example of a rectangular screen separator is illustrated in U.S. Pat. No. 4,582,597, the disclosure of which is incorporated herein by reference. A circular separator is illustrated in U.S. Pat. No. 4,613,432, the disclosure of which is incorporated herein by reference. Each type of separator has its own advantages well known in the industry.
Vibratory separators may also be distinguished by the multiple ways that they provide tensioned screen cloth. One system is to employ untensioned screens using hook strips in association with tensioning mechanisms on the screening system. One such system is illustrated in U.S. Pat. No. 5,221,008. Alternatively, pretensioned screen panels including tensioned screen cloth affixed to rigid frames provide the tensioning mechanism. In such circumstances, tensioning mechanisms on the vibratory separators are avoided. The manufacture of such screens is disclosed in U.S. Pat. No. 4,968,366, the disclosure of which is incorporated herein by reference.
Hook strip screens which are tensioned on the screening device require a crown on the screen bed. Such a crown has proven to be disadvantageous with regard to the distribution of material on the screen. Such devices also require multiple fasteners along the sides of the screen deck which are time consuming to operate and are susceptible to errors in assembly.
Pretensioned screens have been incorporated into vibratory housings in circular screens by including screen frames with outwardly extending mounting flanges that are sandwiched between succeeding wall portions. Reference is made to U.S. Pat. No. 4,810,372, incorporated herein by reference, illustrating such flanges and their placement in the housing. Pretensioned screens which are rectangular have not employed outwardly extending mounting flanges. They have used clamps operating directly on the frame itself. One clamp system employs a pneumatic seal in association with channels to locate and retain such frames. Reference is made to U.S. Pat. Nos. 4,582,597 and 5,226,546, the disclosures of which are incorporated herein by reference.